Why the DC voltage doesn't affect the high pass with the NMOS Transistor?

By changing the gate-source voltage of the NMOS transistor, I can alter the resistance in the triode region. The transistor becomes a voltage-controlled resistor.

I don't understand how it affects the high pass filter and the $$\I_{\text{DS}}\$$ current when I decrease the voltage to 2.0 V.

I decreased the voltage here in V2 and I got this graph.

And for the V2 = 3.3V I have got this result.

Where I can see that the voltage to the gate doesn't affect the high pass filter.

• I can see that it does. But the difference will be easier to see in a frequency response plot. – user_1818839 Feb 26 '18 at 14:52